For conversion of synthesis gas to transportation fuels, conventional Fischer Tropsch (FT) or MTG (Methanol to Gasoline) type processes usually require hydrogen (H2) to carbon monoxide (CO) molar ratios of about 1.8-2.1. This compares to H2:CO ratios of about 0.5 typical for synthesis gas from coal gasification and about 1.0 for biomass gasification. Thus, significant reprocessing (including catalytic sour-shift and carbon monoxide-sulfur (COS) hydrolysis) of such synthesis gas products with low H2:CO ratio is required to increase the H2:CO ratios to the desired 1.8-2.1 range. For Fischer Tropsch processes using specific iron catalysts, a lower H2:CO ratio of about 1-1.2 is acceptable, but leads to:                Significantly lower “per pass H2 and CO conversions” to desirable liquid products which (i) increases the extent of recycle of unconverted syngas to the Fischer Tropsch reactor and (ii) requires additional reforming, either autothermal reforming (ATR) or steam methane reforming (SMR) of a part of the recycle gas.        Significantly higher production of carbon dioxide via shift reactionCO+H2O(steam)→CO2+H2 For a cobalt-based Fischer Tropsch catalyst, the key reaction is CO+2H2→—CH2—+H2O with relatively high carbon utilization. In contrast, for iron-based Fischer Tropsch catalysts, the carbon utilization is significantly reduced due to the formation of carbon dioxide as a byproduct, as the overall reaction is:2CO+H2→—CH2—+CO2         
For the conversion of natural gas to FT-diesel using a catalytic ATR-type syngas generation process where natural gas is reacted with steam and oxygen, it is necessary to recycle a relatively large amount of CO2-rich unconverted syngas from the Fischer Tropsch unit to the ATR unit. This significantly increases the (1) amount of oxygen required for the ATR operation and (2) ATR reactor volume.
With regard to the production of liquid fuels for coal or biomass (coal to liquid, CTL or biomass to liquid, BTL), typical net thermal efficiencies are relatively low compared to those for natural gas to liquid (GTL):                For a Fischer Tropsch process, typical efficiency (lower heating value, LHV basis) for CTL/BTL is about 47-49% with CO2 capture. For GTL the value is about 55-58%.        For a CTL/BTL-methanol to gasoline process, typical LHV efficiency is about 53-54% with carbon capture compared to 62-65% for GTL-methanol to gasoline.        
Coal gasification typically produces synthesis gas with a H2:CO molar ratio too low for integrated gasification combined cycle (IGCC)-based power production or for synthesis reactions to chemicals and fuels with carbon capture, requiring the use of expensive catalytic sour and/or sweet shift reactors to increase the H2:CO molar ratio of the synthesis gas before use. There is a need or desire to reduce the use of these expensive processes.